Question

我正在尝试（太长时间）将DateTime列转换为label.Text。

各种错误：

我错过了什么？

drExpDatesRow = dtAllCompanies.Select("CompanyID = " + CompanyID.ToString())

    Dim ls_ExpiresDateString As String
    If (Not IsDBNull(drExpDatesRow("Expdate"))) Then
        Date.TryParse(drExpDatesRow("Expdate").ToString(), ls_ExpiresDateString)
        'ls_ExpiresDateString = ldt_ExpiresDate.ToString("MM/dd/yyyy")
        lbl_ExpireDate.Text = ls_ExpiresDateString.ToString()
    Else
        lbl_ExpireDate.Text = ""
    End If

System.InvalidCastException未处理Message = Conversion from 字符串“Expdate”键入'Integer'无效 Source = Microsoft.VisualBasic StackTrace：在Microsoft.VisualBasic.CompilerServices.Conversions.ToInteger（String 值）在C：\ inetpub \ zzz.vb中的zzz.winCompanyInfo.CompanyInfo_Load（Object sender，EventArgs e）：第638行在System.Windows.Forms.Form.OnLoad（EventArgs e）在System.Windows.Forms.Control.CreateControl（Boolean fIgnoreVisible）在System.Windows.Forms.Control.CreateControl（）在System.Windows.Forms.Control.WmShowWindow（消息＆amp; m）在System.Windows.Forms.Control.WndProc（消息＆amp; m）在System.Windows.Forms.Control.ControlNativeWindow.WndProc（Message＆amp; m）在System.Windows.Forms.NativeWindow.DebuggableCallback（IntPtr hWnd，Int32 msg，IntPtr wparam，IntPtr lparam）InnerException： System.FormatException 消息=输入字符串格式不正确。来源= Microsoft.VisualBasic程序堆栈跟踪：在Microsoft.VisualBasic.CompilerServices.Conversions.ParseDouble（String Value，NumberFormatInfo NumberFormat）在Microsoft.VisualBasic.CompilerServices.Conversions.ToInteger（String 值）的InnerException：

更新**添加了DataRow逻辑

Answer 1

使用TryParse时，请使用相同的数据类型。

Dim drExpDatesRow = (From dr As DataRow In dtAllCompanies.Rows 
                     Where dr("CompanyId").ToString =
                     CompanyID.ToString).FirstOrDefault

Dim ls_ExpiresDate As Date      ' Date not String
If (Not drExpDatesRow Is Nothing) Then
  If Date.TryParse(drExpDatesRow("Expdate").ToString(), ls_ExpiresDate)
    lbl_ExpireDate.Text = ls_ExpiresDate.ToString()
  End If
Else
    lbl_ExpireDate.Text = ""
End If

Answer 2

您的代码中存在多个问题。这个应该好好处理好事情

drExpDatesRow = dtAllCompanies.Select("CompanyID = " + CompanyID.ToString()) ' returns array

lbl_ExpireDate.Text = ""
If drExpDatesRow.Length > 0 Then

    If (Not IsDBNull(drExpDatesRow(0)("Expdate"))) Then

        Dim myDate As DateTime
        Dim res As Boolean = Date.TryParse(drExpDatesRow("Expdate"), myDate)

        If res Then lbl_ExpireDate.Text = MyDate.ToString("<format>")
    End If
End If

如果不是IsDBNull，则将Date列转换为字符串/标签

2 个答案: